{"id":"F2006B10669","name":"AD/HU 369/11 Amdt 1 - Main Transmission Ring Gear Bolts - Inspection","slug":"ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116602,"registerId":"commonwealth-F2006B10669-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/11 Amdt 1 - Main Transmission Ring Gear Bolts - Inspection","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\n \n\nAD/HU 369/11\n\nAmdt 1\n\n\nMain Transmission Ring Gear Bolts - Inspection 2/79\n\n \n\nApplicability: All model 369H Series except helicopters modified in accordance with HL. 39 (main transmission P/N 369A5100- 705M, -707M, -709).\n\n \n\nDocument: Hughes SIN No. HN-61.\n\n \n\nCompliance: At next scheduled main transmission oil change and thereafter at intervals not exceeding 150 hours time in service after 28 September 1973.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 1 to an existing Airworthiness Directive. The scope remains tightly focused on the original safety issue — inspection of main transmission ring gear bolts on specific helicopter models. There is no indication of scope creep; the amendment appears to maintain the original narrow safety purpose."},"complexity_factors":["Extremely short document — only 8 substantive lines","Single mechanical inspection requirement with straightforward recurring interval","Simple applicability clause with one clear exception","No defined terms section, no cross-references to other legislation, no conditional logic","Single external reference to manufacturer document (Hughes SIN HN-61)","Compliance date is fixed and absolute (28 September 1973 baseline)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific helicopters.\n\n**What it does:**\nIt requires owners and operators of certain McDonnell Douglas (formerly Hughes) and Kawasaki 369 Series helicopters to inspect the **main transmission ring gear bolts** — critical fasteners that hold together a major component of the helicopter's drivetrain.\n\n**Who it affects:**\n- All **Model 369H Series** helicopters\n- **Except** those already modified with specific upgraded main transmission parts (part numbers ending in -705M, -707M, or -709)\n\n**What must be done:**\n- Inspect these bolts at the **next scheduled transmission oil change**\n- Then repeat the inspection **every 150 hours of flight time** (measured from when the helicopter is actually in service, not just sitting on the ground)\n- The clock started ticking on **28 September 1973**\n\n**Why it matters:**\nRing gear bolts in the main transmission are under enormous stress. If they fail, the helicopter could lose power to the rotor system with catastrophic consequences. This AD ensures potential cracks, wear, or loosening are caught before they cause an accident.\n\n**The backstory:**\nThis directive references **Hughes Service Information Notice HN-61**, indicating the manufacturer identified a problem and CASA made compliance mandatory for Australian-registered aircraft."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"This instrument is presented as \"Amdt 1\", indicating it amends an earlier AD. The excerpt itself does not include the original AD text, so the precise substantive changes from the original cannot be determined from this document alone. The presented text specifies applicability (including an exemption for helicopters modified per HL.39), references Hughes SIN HN-61 for procedure, and sets the inspection timing (next oil change, then every 150 hours after 28 September 1973); any differences from the prior version are not shown in the supplied text."},"complexity_factors":["Narrow technical scope limited to inspection of a specific component (main transmission ring gear bolts).","Clear, simple compliance schedule tied to routine maintenance (next oil change; then every 150 hours).","Limited applicability clause with a specific exemption for helicopters modified per HL.39 (requires checking modification records).","Reliance on an external technical document (Hughes SIN HN-61) for inspection procedure increases dependency on that document for operational detail.","Lack of enforcement, alternative compliance or corrective-action detail in the excerpt increases administrative uncertainty for implementers."],"plain_english_summary":"This AD requires operators of all Model 369H series helicopters (except those modified per HL.39) to inspect the main transmission ring gear bolts using Hughes Service Instruction Notice HN‑61.  \n\nInspections must occur at the next scheduled main transmission oil change and repeat at intervals not exceeding 150 flight hours (effective from 28 September 1973); operators/owners arrange and pay for the work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection","history":"/api/acts/ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection/history","analysis":"/api/acts/ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection/analysis","conflicts":"/api/acts/ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection/conflicts","importantCases":"/api/acts/ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection/important-cases","documents":"/api/acts/ad-hu-369-11-amdt-1-main-transmission-ring-gear-bolts-inspection/documents"}}